In the prior art, herbal extracts and tinctures are commonly made using one or more solvents to extract one or more active principles contained in the herbaceous raw material being treated. Extraction techniques used to date include either percolation or maceration techniques.
U.S. Pat. No. 4,952,603 to Elferaly et al. teaches a method of isolation of artemisinin from Artemisia annua. In this method, dried unground leaves of Artemisia are extracted by continuous hot percolation over a period of 48 hours using n-hexane as a solvent. Hot percolation is akin to the percolation of coffee wherein the liquid is heated to boiling to achieve extraction of the material being treated.
Another known technique for the extraction of active principles from an herbaceous material is maceration In this process, the herbaceous material is combined with one or more solvents and allowed to steep for a period of time, usually 14–38 days. The batch is usually mixed or stirred twice daily. During this steeping period, the active principles are extracted into the solvent and the active principle-containing solvent is drawn off after the period of steeping is complete.
The prior art also uses a percolation system whereby the solvent is merely allowed to percolate or pass through the herbaceous raw material.
FIG. 1 shows an exemplary percolation apparatus designated by the reference numeral 10. In this process, a conical or cylindrical vessel 1 with a stopcock 3 at the base thereof is used. The vessel is supported by members 4. The vessels can be made of glass, copper or stainless steel. Typically, the depth of the material to be processed is about 5 times the diameter of the cylindrical percolator. For example, a percolator having a 4.5-inch diameter would require a column height of 22.5 inches for the material. Prior to the actual percolation, the material is comminuted to a particular size and soaked in the solvent or menstruum to be used for about 2 hours. This allows the material to swell prior to being charged to the percolator vessel. The comminution should be sufficient to allow the material to be in contact with the solvent but should not be too fine to cause clogging during the percolation process. The degree of comminution depends on the herbaceous material. For most herbs, a tealeaf cut is preferred, i.e., having particles the size of tealeaves.
Prior to charging the vessel, a sieve plate 5 and a wad of cotton or filter paper 7 are placed in the vessel 1, preferably in the neck thereof, to prevent the stopcock 3 from clogging. The sieve plate 5 also supports the charge of material 9.
The pre-swollen drug as the charge, also known as the marc, is then placed in the vessel 1 on top of the sieve plate 5, and distributed so that channels are not formed that would allow uneven flow of the solvent through the marc 9.
The marc 9 is then covered with filter paper 11, weighted down with glass beads 13, and covered with a lid 15. The solvent is then poured onto the filter paper/glass bead layer and allowed to saturate the marc 9. The stopcock is open during this step to force air out of bottom of the vessel and through the stopcock.
As soon as the liquid 21 begins to drip out into the beaker 23, the stopcock 3 is closed and the marc is allowed to macerate for a period of about 24 hours. The extract is then allowed to drip out at a percolation rate of about 4–6 drops per minute for each 100 grams of crude material. For 1000 grams of material, the rate would be 40–60 drops per minute.
The first run of the solvent has the highest percentage of active principles and is commonly referred to as first runnings or extraction head. The first runnings generally extract about 45% of the active principles. A second run or pass would produce an extract with about 23% with a third run or pass having about 12%. A fourth pass would have about 3% and a fifth pass has about 1%. In this one through process, there is an ever-diminishing return with about 84% of the active principles recovered.
The prior art techniques mentioned above have drawbacks that hinder the efficient and effective extraction of active principles from herbaceous raw materials. In the percolation technique, production is very slow and only about 45% of the active principles are recovered at best in the first runnings. In addition, solvent evaporation is high, thus contributing to increased costs.
Maceration techniques take too long, and only recover 35–38% of the active principles from the herb. The prior art percolation technique fails in its ability to extract many of the active principles in the herb and is also slow in its once through processing.
As such, a need has developed to provide improved ways to extract active principles from herbs/plants that overcome the disadvantages known in the prior art. The present invention solves the prior art problems by providing a method and apparatus that extracts active principles from herbaceous raw materials more economically and in concentrations providing enhanced medicinal effects to users.